The present invention relates to a hybrid drive system that includes a rotating electric machine; an input member that is drive-coupled to an internal combustion engine and the rotating electric machine; an output member that is drive-coupled to a wheel; a speed change device that has a plurality of switchable shift speeds, and changes the rotational speed of the input member at respective speed ratios of the shift speeds and transmits the changed rotational speed to the output member; and a control device that at least performs an operation control for the rotating electric machine.